Case Study Shows Benefits of Applying Hollow Glass Spheres to Drilling Fluids

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 174010, “Hollow-Glass-Sphere Application in Drilling Fluids: Case Study,” by Arminder Minhas, SPE, Halliburton; Brandon Friess, SPE, Farid Shirkavand, and Barry Hucik, Seven Generations Energy; Teresa Pena-Bastidas, 3M Canada; Bradley Ross, SPE, Halliburton; and Shawn Servinski and Frank Angyal, Seven Generations Energy, prepared for the 2015 SPE Western Regional Meeting, Garden Grove, California, USA, 27–30 April. The paper has not been peer reviewed. In an effort to optimize drilling operations and economics, an operator examined the effect of adding hollow glass spheres (HGSs) directly to the drilling fluid instead of performing underbalanced drilling. Both nitrogen and HGSs were believed to reduce hydrostatic pressure of the mud column in the hole, resulting in higher drilling rates of penetration (ROPs) and reduced mud losses to the wellbore. This paper provides information on HGSs as an economic alternative to nitrogen to help reduce the hydrostatic pressure of invert-emulsion drilling fluids. Introduction This case study focuses on the application of HGSs in two different sections of the drilling operation—a horizontal section and a vertical intermediate section. Data from a base-case horizontal section using an all-oil drilling fluid were compared with data of another well on the same drilling pad using the same fluid with the addition of HGSs. The intermediate-section data were from a base-case well that used an invert-emulsion drilling fluid, and they were compared with data from other intermediate well intervals in the same field that used an invert-emulsion drilling fluid with the addition of HGSs. Use of HGSs in Drilling Fluids HGSs are inert materials that are used as density-reducing agents. In the oil and gas industry, they are used for reducing the density of drilling fluids and cement blends. These hollow spheres (Fig. 1) are chemically inert, thermally stable (with a softening temperature of 600°C), and made of soda-lime borosilicate with a high strength/density ratio, and they can be added to both oil- and water-based fluids. A density reduction of up to 2.086 lbm/gal is possible when using HGSs. HGS addition helps reduce density and, consequently, the effective circulating density (ECD). Addition of HGSs to a lightweight drilling fluid allows consistent, stable properties and allows for measurement while drilling and controlled management of fluid properties. These lightweight fluids can be used for drilling at balanced, near-balanced, or underbalanced conditions. Applications include depleted reservoirs, geologically fractured formations, poorly consolidated formations, and high-permeability formations. In general, a reduction of differential pressure can result in the elimination of differential sticking, reduction or elimination of fluid loss, and mitigation of formation damage. This can result in higher productivity during drilling operations and during production.